1. Field of the Invention
The present invention relates to a hologram recorder that records a hologram by causing interference between a recording beam and a reference beam on a hologram recording medium, and to a method of recording the hologram.
2. Description of the Related Art
A conventional hologram recorder is disclosed in JP-A-2006-145676, for example. This hologram recorder splits a laser beam emitted by a light source into a recording beam and a reference beam with a beam splitter, and modulates the recording beam with a spatial light modulator according to information to be recorded. Then the recording beam and the reference beam are caused to interfere with each other on a hologram recording medium, thereby recording holograms. Between the light source and the beam splitter, a beam shaper is provided for equalizing the intensity distribution of the laser beam. The hologram recorder with such beam shaper can shape the laser beam that presents a Gaussian intensity distribution pattern into a beam with an equalized intensity distribution, and also the recording beam emitted by the spatial light modulator into a beam with an equalized intensity distribution. Such hologram recorder can record a hologram composed of an interference fringe pattern having a uniform contrast, thereby minimizing reading errors when reconstructing the hologram.
In the conventional hologram recorder, however, the beam shaper includes a combination of special aspherical lenses, and such beam shaper has to be strictly accurately positioned in the recorder, which requires complicated designing and manufacturing process, as well as a high cost.